A grindstone is a tool formed of hard particles, namely, abrasive grains with binding agents. Processings using the grindstone include grinding and polishing, and in general, rough processing is referred to as grinding, and finishing is referred to as polishing. These processings are the processing to scrape a workpiece surface, namely, a surface to be processed with the abrasive grains into debris by relatively moving a grindstone and the workpiece while the grindstone is being pushed against the workpiece. In the present specification, note that grinding/polishing indicates both grinding and/or polishing.
The grinding/polishing processing using a grindstone includes: cylindrical grinding/polishing to process a cylindrically-shaped outer peripheral surface of a workpiece; inner surface grinding/polishing to process a cylindrically-shaped inner peripheral surface of a workpiece; and flat surface grinding/polishing to process a flat surface of a workpiece. As the grindstone to process the outer peripheral surface and the inner peripheral surface, a grindstone provided with a cylindrically-shaped working surface is used. Further, as a grindstone to process a flat surface, a cylindrically-shaped grindstone provided with a working surface on an outer peripheral surface or a grindstone having a cup-shape, a ring-shape, or a disk-like shape and including a working surface on a flat side surface is used.
In relation to the grindstones, various kinds of methods are proposed in the related arts. For example, JP 63-150163 A (Patent Literature 1 listed below) discloses a grindstone with a structure including a three-dimensional net-like composition where abrasive grain particles are bonded with synthetic resin and continuous pores are provided, wherein a volume ratio of the abrasive grains, bonding strength, etc. are specified. The invention disclosed in Patent Literature 1 is similar to the present invention in a point of, for example, having a structure where the abrasive grains are bonded with the synthetic resin.
Further, JP 64-40279 A (Patent Literature 2 listed below) discloses a polishing tool member in which abrasive grains are ceramic fibers or metal wires in an abrasive fixed type polishing member in which the abrasive grains are fixed on a bond layer, and the fibers wires are arranged such that longitudinal sides thereof intersect with a polishing surface.
Additionally, JP 2000-198073 A (Patent Literature 3 below) discloses a polishing grindstone including: aggregated abrasive grains formed by aggregating a plurality of ultra-fine abrasive grains; and a resin that forms a grindstone by kneading and solidifying the aggregated abrasive grains. However, the inventions disclosed in Patent Literatures 1 to 3 are different in a point of not including grindstone pillars arranged in parallel and each having an axis L in a depth direction of a grinding/polishing surface, unlike the present invention.